Pulmonary complications, often related to smoke inhalation, have become the major cause of burn death. At the present time, treatments, e.g., corticosteroids, are non-specific, and often result in serious side effects, such as inceased pulmonary bacterial susceptibility. Clinical research has been unrewarding because of the multiple variables, and the need to treat the patient. Using a specially designed smoke exposure apparatus, which permits on-going environmental and physiological monitoring, a smoke rat model has been developed. Animals that are exposed to white pine smoke, for 15 minutes, in this apparatus, initially appear normal to all observations, then develop bronchospasm, hypoxia, and acidosis, with interstitial edema, hyaline membranes, and atelectasis. The mortality rate is 44 percent, with an average survival time of 20 hours post exposure. It is the objective of this research to create those pathophysiologic changes found in patients, i.e., bronchospasms, atelectasis, hyaline membrane formation, in order to describe the mechanism involved, and to develop methods of therapy.